ec2-snapshot.bash-dist

#!/bin/bash

# This work is licensed under a
# Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
# http://creativecommons.org/licenses/by-nc-sa/3.0/
#
# Delete snapshots except the last "keep" number for the given description.
# Create new snapshot of vol_id, label with given description.
# No guarantees. Use at your own risk.
#
# CHANGELOG:
# 2010-08-31
#  Now sorts the snapshot list before doing anything else, so that diagnostic output will also be sorted.
# 2010-08-24
#  Volume ID will be passed as first parameter now.
# 2010-08-24
#  First version

export EC2_PRIVATE_KEY=~/.ssh/pk-.pem
export EC2_CERT=~/.ssh/cert-.pem

# Volume to backup
vol_id=$1
# Use a simple string for the description
description="$2"
# How many snapshots to keep
keep=$3


usage() {
    cat <<EOT
ec2-snapshot.bash volume-id description n
    description = a simple string
    n = number of snapshots to keep, it'll delete all but the last n
    snapshots
EOT
exit
}

if [ "$vol_id" == "" ]; then usage; fi
if [ "$description" == "" ]; then usage; fi
if [ "$keep" == "" ]; then usage;fi

#set -v # verbose
#set -x # echo
# Sample outputs:
#$ ec2-create-snapshot -d "DESCRIPTION" vol-12345678
#SNAPSHOT    snap-12345678   vol-12345678    pending 2010-08-24T10:00:00+0000        680505800880    1   DESCRIPTION
#$ ec2-describe-snapshots 
#SNAPSHOT    snap-12345678   vol-12345678    completed   2010-08-24T10:00:00+0000    100%    680505800880    1 DESCRIPTION


# get snapshot list. sort -k5 sorts on the 5th field (date). head -n -$keep
# returns all but the last $keep lines.
snaps=`ec2-describe-snapshots -o self | grep completed | grep $vol_id | grep "$description" | sort -k5`

snap_status() {
    msg=$1
    shift
    echo `echo $@ | grep -o SNAPSHOT|wc -w` $msg
    echo $@ | sed "s/SNAPSHOT/\nSNAPSHOT/g;"
}

snap_status "snapshots:" $snaps

# cat, because echo eats newlines.
snaps_to_delete=`cat<<EOT | head -n -$keep
$snaps
EOT
`
snap_status "snapshots will be deleted:" $snaps_to_delete

snap_ids=`cat<<EOT | cut -f2
$snaps_to_delete
EOT`

echo Deleting...
for snap in $snap_ids
do
    ec2-delete-snapshot $snap
done

ec2-create-snapshot -d "$description" $vol_id